Quarter 2 Environmental Science Vocabulary

Comprehensive vocabulary flashcards for the Quarter 2 Environmental Science exam scheduled for November 4th, covering Earth systems, ecological concepts, soil science, and scientific inquiry.

A horizon

The topsoil layer of a soil profile, composed of mineral particles mixed with decomposed organic matter (humus), crucial for plant growth and agricultural productivity.

Abiotic

Non-living physical and chemical components of an ecosystem that influence living organisms, including solar radiation, temperature, precipitation, wind, and soil pH.

Adaptation

A heritable genetic trait developed over generations that improves an organism's survival and reproductive fitness within its specific environmental conditions.

Albedo effect

The fraction of incoming solar radiation reflected by a surface, where high-albedo surfaces like ice reflect significant energy and low-albedo surfaces like open ocean absorb heat.

Asthenosphere

The semi-fluid, ductile upper portion of the mantle located directly below the lithosphere, facilitating the movement of Earth's tectonic plates through convection.

Atmosphere

The envelope of gases surrounding Earth held by gravity, primarily composed of approximately $78\%$ nitrogen ($\text{N}_2$) and $21\%$ oxygen ($\text{O}_2$).

B horizon

The subsoil layer beneath the topsoil where leached minerals, clays, aluminum, and iron compounds accumulate from upper horizons (zone of accumulation).

Biogeography

The study of the geographic distribution of species and ecosystems across space and through geological time, such as in the theory of island biogeography.

Biological Oxygen Demand (BOD)

The amount of dissolved oxygen required by aerobic aquatic microorganisms to decompose the organic matter present in a water sample over a specific time period.

Biotic

The living or once-living biological organisms within an ecological community, including producers, consumers, and decomposers.

C horizon

The soil horizon consisting of partially weathered parent rock material located directly beneath the subsoil and sitting atop solid unweathered bedrock.

Carnivore

A secondary or higher-level consumer that obtains metabolic energy and biomass predominantly or exclusively by consuming other animals.

Cation Exchange Capacity (CEC)

The total measure of a soil's ability to hold and exchange positively charged nutrient ions (such as $\text{Ca}^{2+}$, $\text{Mg}^{2+}$, and $\text{K}^{+}$), serving as a vital indicator of soil fertility.

Climax community

A mature, stable, and diverse ecological community that has reached the steady final stage of ecological succession under prevailing environmental conditions.

Constant(s) (science)

Experimental variables and conditions kept strictly uniform across all trials to isolate the direct effect of the independent variable.

Control group

The baseline group in a scientific experiment that is not subjected to the experimental treatment, serving as a standard of comparison.

Controlled experiment

A scientific investigation designed so that only one independent variable is manipulated while all other potential confounding variables are held constant.

Convergent plate boundary

A tectonic boundary where lithospheric plates move toward one another, resulting in subduction zones, deep ocean trenches, volcanic arcs, or continental mountain ranges.

Coriolis Effect

The deflection of moving air and water currents caused by Earth's rotation, turning trajectories to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

Cultural Ecosystem Service

Non-material benefits derived from natural ecosystems that enrich human well-being, such as aesthetic enjoyment, spiritual fulfillment, recreation, and ecotourism.

Decomposer

An organism that chemically breaks down dead organic matter and animal wastes into simpler inorganic molecules, cycling nutrients back into the ecosystem.

Dependent variable

The factor measured and observed in an experiment that changes in response to the manipulation of the independent variable.

Directional Selection

A pattern of natural selection that favors individuals at one extreme of a phenotypic distribution, driving a directional shift in population allele frequencies.

Disruptive Selection

A pattern of natural selection favoring individuals at both phenotypic extremes while selecting against intermediate phenotypes, which can promote speciation.

Dissolved Oxygen (DO)

The concentration of free, unbonded oxygen molecules circulating in water, vital for the cellular respiration of fish and other aquatic organisms.

Divergent plate boundary

A tectonic boundary where lithospheric plates move apart from each other, creating new oceanic crust along mid-ocean ridges or forming continental rift valleys.

Downwelling

The downward movement of oxygen-rich, dense surface water to deeper ocean depths, ventilating the deep sea and supporting benthic ecosystems.

E horizon

A pale, heavily leached soil horizon positioned between the A and B horizons characterized by the eluviation of silicate clay, iron, and organic matter.

El Nino Southern Oscillations (ENSO)

A recurring tropical Pacific climate pattern featuring weakened trade winds, warmer sea surface temperatures in the central and eastern Pacific, and suppressed coastal upwelling.

Early Successional Species

Opportunistic, fast-growing species that first colonize newly cleared or disturbed ground, marked by rapid reproductive maturity, high seed dispersal, and high light requirements.

Ecological Tolerance

The range of physical and chemical environmental conditions (such as temperature, salinity, and pH) within which a species can survive, grow, and reproduce.

Ecosystem Services

The varied environmental benefits and natural life-support processes provided by healthy, functioning ecosystems that directly or indirectly sustain human life and economies.

Eutrophication

The ecological process where water bodies receive excessive nutrient inputs (especially nitrogen and phosphorus), resulting in algal blooms, bacterial decomposition, and severe hypoxia.

Experimental Groups

The treatment groups within a scientific experiment that are subjected to variations of the independent variable being tested.

Flood plain

A flat, low-lying alluvial landscape bordering a river channel that absorbs overflow during flood stages, depositing nutrient-rich sediments that enhance agricultural fertility.

Generalist species

A species with a broad ecological niche capable of thriving in diverse environmental conditions and consuming a wide variety of food sources.

Heterotroph

An organism that cannot synthesize its own organic nutrients and must consume other organisms or their organic byproducts for energy and growth.

Hypothesis

A proposed, testable, and falsifiable scientific explanation formulated to predict or account for observed phenomena.

Indicator species

A biological species whose presence, absence, population size, or health reveals early warning signals regarding environmental conditions or habitat disruption.

Independent variable

The specific factor or variable intentionally manipulated or altered by the researcher in an experiment to evaluate its outcome.

Late Successional Species

Shade-tolerant, slow-growing, long-lived plant species that replace pioneer communities and come to dominate mature climax ecosystems.

Leaching

The downward transport of dissolved organic materials and mineral nutrients through soil horizons by percolating groundwater.

Lithosphere

The rigid, brittle outer shell of Earth consisting of the crust and uppermost solid mantle, divided into dynamic tectonic plates.

K-selected species

Species characterized by low reproductive outputs, substantial parental care, slow individual growth, large body sizes, and population densities that stabilize near carrying capacity ($K$).

Keystone species

A species that exerts disproportionate control over community biodiversity and food web structure relative to its numerical abundance or biomass.

Mantle Convection Cell

A circular convective loop of semi-solid rock in Earth's mantle driven by internal thermal energy, serving as the primary mechanism driving plate motion.

Mesopause

The atmospheric boundary layer separating the mesosphere from the thermosphere, representing the coldest point in Earth's entire atmosphere.

Mesosphere

The atmospheric layer situated above the stratosphere extending from roughly $50\,\text{km}$ to $85\,\text{km}$, where temperatures decrease with altitude and most meteoroids burn up.

O horizon

The uppermost surface soil layer consisting predominantly of organic detritus, un-decomposed leaf litter, decomposing plant tissue, and humus.

Oligotrophic

An aquatic body characterized by low dissolved nutrient levels, low primary productivity, high water clarity, and high dissolved oxygen concentrations throughout.

Permeability

The rate and capacity with which fluids (water and air) pass through the interconnected pore spaces of soil, sediment, or porous rock.

Physical weathering

The mechanical breakdown of rocks and minerals into smaller fragments without altering their chemical composition, driven by factors like frost wedging and thermal stress.

Porosity

The percentage of total volume occupied by open void spaces between mineral particles within a soil, sediment, or geological formation.

Pioneer species

Hardy initial colonizers, such as lichens and mosses, that establish themselves on barren, soil-less rock substrates and initiate the process of pedogenesis.

Primary consumer

An herbivorous organism at the second trophic level that obtains energy directly by consuming photosynthetic or chemosynthetic autotrophs.

Primary productivity

The rate at which radiant solar or chemical energy is captured and converted into organic biomass by autotrophs per unit area over time.

Primary succession

Ecological succession that initiates on completely barren, newly formed substrate devoid of pre-existing vegetation and biological soil, such as cooled lava flows or retreating glaciers.

Provisioning ecosystem service

Direct material products and commodities extracted from ecosystems for human consumption or use, including timber, freshwater, food, fiber, and medicinal compounds.

Pycnocline

A layer in an aquatic body where water density increases rapidly with depth, driven by steep vertical variations in temperature or salinity.

r-selected species

Opportunistic species characterized by high reproductive capacity, small body size, rapid development, early sexual maturity, minimal parental investment, and boom-and-bust population dynamics.

Rain Shadow Effect

A climatic pattern where prevailing moist air masses release precipitation on the windward slope of a mountain range, creating dry, arid conditions on the sheltered leeward slope.

Regulating Ecosystem Service

Environmental benefits derived from the natural regulation of ecosystem processes, including climate moderation, carbon sequestration, flood mitigation, water filtration, and pollination.

Respiration

The cellular process wherein organisms break down glucose in the presence of oxygen to release usable chemical energy ($\text{ATP}$), yielding carbon dioxide ($\text{CO}_2$) and water ($\text{H}_2\text{O}$).

Riparian zones

Distinct, vegetated terrestrial buffer strips bordering rivers, streams, and wetlands that intercept agricultural runoff, reduce bank erosion, and provide wildlife habitat.

Secondary succession

Ecological succession that takes place in a disturbed ecosystem where pre-existing vegetation was cleared but the soil foundation and seed bank remain intact.

Soil Horizon

A distinct horizontal zone or layer within a soil column characterized by unique physical composition, biological activity, and chemical properties.

Soil Profile

A complete vertical cross-section of a soil column displaying all natural horizons from the surface organic layer down to the underlying bedrock parent material.

Soil Texture

The relative proportion of mineral particle size fractions—specifically sand, silt, and clay—that determines soil porosity, permeability, and water-holding capacity.

Soil Triangle

A ternary diagram used in pedology to determine the textural classification of a soil sample based on relative percentages of sand, silt, and clay.

Specialist species

A species with a narrow ecological niche requiring specific habitat conditions, precise dietary resources, and showing high vulnerability to environmental disruption.

Species Diversity

An ecological metric that accounts for both the total count of distinct species (richness) and the relative proportion of individuals within each species (evenness).

Species Evenness

The measure of the relative abundance, equitability, and balance of individual organisms among all distinct species living within a biological community.

Species Richness

The absolute count of distinct biological species present within a given ecosystem, community, or defined geographic area.

Stabilizing Selection

Natural selection that selects against phenotypic extremes while favoring intermediate traits, thereby reducing population variance in a stable environment.

Stratopause

The atmospheric boundary layer marking the top of the stratosphere where temperatures reach a local peak due to ozone absorption of incoming ultraviolet radiation.

Stratosphere

The atmospheric layer positioned above the troposphere containing the ozone layer ($\text{O}_3$), which filters out harmful incoming solar ultraviolet (UV-B and UV-C) radiation.

Subduction Zone

A convergent plate margin where a dense oceanic slab sinks underneath a lighter continental or oceanic plate into the mantle, generating volcanism and deep earthquakes.

Supporting Ecosystem Service

Fundamental, underlying natural processes—such as nutrient cycling, primary production, and soil formation—that are essential for sustaining all other ecosystem services.

Sustainability

The management and consumption of natural resources at a rate that allows natural replenishment, meeting present human societal needs without compromising future generations.

Thermosphere

The high atmospheric layer above the mesosphere where intense absorption of solar X-rays and UV radiation causes kinetic temperatures to escalate dramatically with altitude.

Threatened species

A species whose wild population numbers are declining significantly, putting it at high risk of becoming endangered across all or a substantial portion of its range.

Transform fault

A tectonic boundary where plates slide horizontally past one another, resulting in shallow seismic activity without the creation or destruction of lithosphere.

Tropopause

The boundary layer of the atmosphere separating the weather-active, convective troposphere from the calm, temperature-inverted stratosphere above.

Troposphere

The lowest layer of Earth's atmosphere extending up to approximately $12\,\text{km}$, containing roughly $75\%$ of atmospheric mass and virtually all weather phenomena.

Upwelling

The oceanographic phenomenon where offshore winds push surface waters away from coastlines, allowing cold, nutrient-rich deep water to ascend to the photic zone.